The present invention relates to twine dispensing mechanisms for wrapping bales, formed in the chambers of large round balers, with twine and more specifically relates to double twine arm arrangements for introducing twine into the chambers of such balers.
U.S. Pat. No. 4,457,226 granted to Meiers on July 3, 1984 shows an automatically actuated and controlled twine wrapping mechanism which employs a single twine arm driven by gearing oscillated by an extensible and retractable hydraulic actuator to cycle a twine dispensing end of the twine arm between opposite sidewalls of the bale forming chamber for causing a bale to be wrapped with spiral wraps of twine. The baler must be stopped during the time a bale is being wrapped and consequently it is desirable to shorten the time required for wrapping the bale. The cycle speed of the arm may be adjusted; however, this also adjusts the number of wraps or wrap spacing of twine applied to the bale and such adjustment may not be desirable.
Twine wrapping mechanisms employing pairs of gear-driven, twine dispensing arms have been developed for shortening twine wrapping cycle time. These developments are exemplified by the mechanisms disclosed in U.S. Pat. Nos. 4,158,331 issued June 19, 1979: 4,167,844 issued Sept. 18, 1979 and 4,253,389 issued Mar. 3, 1981. One problem with these designs is that they are not applicable for use with balers having relatively narrow bale chambers since a dispensing arm must be relatively long in order for its dispensing end to sweep a relatively shallow arc when dispensing and the space availability for mounting two arms without interfering with one another and with other structure is lacking on a narrow baler. Further, no way is provided for adjusting the spacing between wraps other than by adjusting the cycle speed of the arms.
U.S. Pat. No. 4,446,783 issued May 8, 1984 discloses a twine arm assembly which overcomes the space problem, associated with the patented devices discussed in the immediately preceding paragraph, by mounting two dispenser tubes on a single support arm. However, this assembly still does not provide means for adjusting the spacing of wraps of twine on the bale without modifying the cycle speed of the arm.